Syphilis Serology 1 Flashcards
What is the causative agent of syphilis?
Treponema pallidum
Signs and symptoms associated with the Early Primary stage syphilis
Chancre at site
Signs and symptoms associated with the Late Primary Stage of syphilis
Chancre healing
Signs and symptoms associated with the Secondary Stage of syphilis
Skin rash, mucous membrane lesions
Signs and symptoms associated with the Early Latent Stage of syphilis
No symptoms
Signs and symptoms associated with the Late Latent Stage of syphilis
No ssmptoms
Signs and symptoms associated with the Tertiary Stage of syphilis
Systemic (cardiac, skeletal, CNS)
Darkfield Examination of Syphilis:
- appropriate specimen for testing
Only direct exam for treponemes. Collected from lesions (chancres, rash)
Darkfield Examination of Syphilis:
- procedure
Sample collected from lesions, and examined by dark field microscopy (looking for motility of treponemes)
Darkfield Examination of Syphilis:
- appearance of a positive
- appearance of a negative
Positive: Treponemes move in a definite direction using corkscrew or spiraling motility.
Negative: Non-pathogenic ttreponemes move randomly with inchworm style motility
Darkfield Examination of Syphilis:
- stages where this test is helpful
Primary and Secondary stages because of collection type (lesions)
Darkfield Examination of Syphilis:
- technical factors that limit the usefulness
- useful only when lesions present
- cumbersome (warmth, time limit)
- difficult to tell pathogenic from non-pathogenic
Why are VDRL and RPR called “non-treponemal” tests?
Tests are not testing for antibodies against treponemes, only anti-tissue antibodies
What is the definition of cardiolipin
(antigen) non nitrogenous phospholipid found in many plant and animal tissues
Definition of reagin
non-specific anti-tissue antibodies NOT antibodies agains treponemes
Sensitivity of Non-treponemal tests during early primary stage of syphilis
Negative
Sensitivity of Non-treponemal tests during late primary stage of syphilis
Positive (titers increasing)
Sensitivity of Non-treponemal tests during secondary stage of syphilis
Postive (titers high)
Sensitivity of Non-treponemal tests during early latent stage of syphilis
Positive (titers declining)
Sensitivity of Non-treponemal tests during late latent stage of syphilis
Positive? (titers declining)
Sensitivity of Non-treponemal tests during tertiary stage of syphilis
50% may revert to negative
What diseases may produce falsely positive results in the non-treponema tests for syphilis?
Other disease states/conditions have these antibodies (ex. pregnancy) The test can be too sensitive which leads to biological false positives.
How are non-treponemall tests used to monitor treatment of syphilis
Useful because once treated successfully the disease goes away (you can get it again!) so you can monitor successful treatment
How are non-treponemal tests used to identify re-infected with syphilis
Reagin antibodies are present in infection and then disappear with treatment making it easy to detect reinfection
Meaning of VDRL
Veneral Disease Research Laboratory
Serologic principle for VDRL
flocculation
flocculation vs direct agglutination
Flocculation causes the antigen substance to be cloudy due to added substances that enhance the visibility of the reaction
VDRL
- testing procedure
Cardiolipin antigen and patients SERUM mixed on glass microscope slide to detect reagin antibodies
(serum must be heat inactivated for 30 minutes at 56C prior to testing)
VDRL
- test results read micro or macroscopically
microscopically
VDRL
- Appearance of reactive, weakly reactive, and non-reactive controls
Reactive: distinctive chunks
Weakly Reactive: smaller chunks
Nonreactive: cloudy
Meaning of RPR
Rapid Plasma Reagin
RPR
- serologic principle
flocculation
RPR
- procedure
uses cardiolipin-lecithen-cholesterol antigen with carbon particles.
RPR
- observed micro or macroscopically
macroscopically
RPR
- appearance of reactive, weakly reactive, and non-reactive controls
Reactive: big darker chunks
Weakly Reactive: smaller chunks with hazy background
Nonreactive: clear and/or swirling tail
VDRL v.s RPR
- sensitivity, specificity, and ease of performance
Have about the same sensitive and specificity for testing serum. RPR is NOT approved for CSF testing.
- easier to do RPR because you have to heat inactivate
VDRL v.s. RPR
- significance of a weakly reactive result
May be due to prozone with an increased amount of antibody present
VDRL and RPR
- further testing for reactive or weakly reactive
must be tested quantitatively by the VDRL/RPR test and then confirmed by a treponema antibody detection method
What is the only syphilis assay approved for testing spinal fluid?
VDRL
